(a) Field of the Invention
The present invention relates to a photolithography system, and a method for fabricating a thin film transistor array substrate using the same.
(b) Description of the Related Art
Generally, a semiconductor device is formed through depositing a plurality of thin films onto a substrate, and repeatedly etching the thin films by a photolithography using a photoresist.
In the photolithography process, a photoresist film is first deposited onto the uppermost thin film, and baked through soft baking. Thereafter, the photoresist film is exposed to light using a mask, and selectively removed using a developing solution. The resulting photoresist pattern goes through hard baking, and the underlying thin films are selectively removed using the photoresist pattern as a mask. In this way, the thin film patterns are completed.
In the light exposing process, the shape of masks or the construction of shots may differentiate the amount of light illuminated on the photoresist film. As the light exposing time is longer than the time for depositing or developing the photoresist film, it is required for improving productivity in the photolithography process to effectively control the light exposing process.
Meanwhile, a liquid crystal display has a thin film transistor (TFT) array substrate, a color filter substrate facing the TFT array substrate, and a liquid crystal layer sandwiched between the TFT array substrate and the color filter substrate.
In the TFT array substrate, TFTs and lines are formed on an insulating substrate through depositing thin films on the substrate and repeatedly performing the photolithography process with respect to the thin films. In order to simplify the steps of fabricating such a TFT array substrate, it has been suggested that a minute slit pattern where the slit size is so small as to exceed the decomposing capacity of the light exposure, or a separate film having a different light transmission is formed at the mask, and a photoresist pattern having a portion with a half thickness is formed using such a mask to thereby pattern one or more of the underlying thin films through one photolithography process. However, in such a technique, it is difficult to form uniform patterns over the entire area of a large-sized substrate.